PLANTS COMMUNICATE USING AN INTERNET OF FUNGUS

Gardeners, keep an eye on your tomato plants. There's no knowing what they are plotting underground.

Some 80 per cent of plants are colonised by fungi that form the familiar network of fine white threads that hang off many roots. The threads, called mycorrhizae, take in water and minerals from the soil, and hand some over to the plant in exchange for nutrients. Now it seems plants use them to communicate too.

Ren Sen Zeng and colleagues at South China Agricultural University in Guangzhou, grew pairs of tomato plants in pots. The team allowed some pairs to form mycorrhizal networks between their roots. Plants connected this way can exchange nutrients and water, staving off the effects of drought. But Zeng wanted to know if the networks had any other function.

The team sprayed one plant in each pair with Alternaria solani, a fungus which causes early blight. Sixty-five hours later, they infected the second plant and observed how well it coped.

Plants sharing a mycorrhizal network were less likely to develop the blight, and when they did, symptoms were milder. They were also more likely to activate defensive genes and enzymes (PLoS One, DOI: 10.1371/journal.pone.0013324).

The first plant was signalling to its neighbour, Zeng says, and he has dubbed mycorrhizae "the internet of plant communities".